title: Extraction, structural characterisation and evaluation of hydroxycinnamate esters of orchard grass (Dactylis glomerata) as substrates for polyphenol oxidase.
abstract: Polyphenol oxidase (PPO) activity has been reported in orchard grass (Dactylis glomerata); however, to date, no endogenous substrates have been identified. In the present study, we report the isolation and structural elucidation of PPO substrates in this species. The free phenol fraction was extracted, separated by reverse-phase chromatography and six potential substrates, including two hydroxycinnamate esters, were identified by UV spectrometry, electrospray ionisation-tandem mass spectrometry (LC-ESI-MS(n)) and 1D and 2D NMR analyses ((1)H NMR, (13)C NMR, DEPT, COSY, HMQC and HMBC). Furthermore, three caffeoylquinic acids (3-CQA, 4-CQA and 5-CQA) were identified by comparison of their spectral data (ESI-MS) with those of known compounds and literature data. Five of these compounds were demonstrated to be substrates for orchard grass PPO.
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Plas Gogerddan, Aberystwyth, Wales SY23 3EB, UK. ifp@aber.ac.uk
authors.forename: Ifat
authors.initials: I
authors.lastname: Parveen
authors.forename: Ana
authors.initials: A
authors.lastname: Winters
authors.forename: Michael D
authors.initials: MD
authors.lastname: Threadgill
authors.forename: Barbara
authors.initials: B
authors.lastname: Hauck
authors.forename: Phillip
authors.initials: P
authors.lastname: Morris
mesh_terms: D004156:Catechol Oxidase / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D031745:Dactylis / Q000737:chemistry* / Q000201:enzymology; D004952:Esters; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification; D021241:Spectrometry, Mass, Electrospray Ionization; D013379:Substrate Specificity
chemical_list: D003373:Coumaric Acids; D004952:Esters; D010636:Phenols; D004156:Catechol Oxidase